It’s complicated. Chiang Kai-shek was a historical adversary of the CPC and is viewed as a traitor and war criminal in the PRC. However, his nationalist party, the KMT, is alive and well in Taiwan. The CPC currently favors the KMT even though they were former adversaries because the KMT advocates for deepening economic ties to the PRC.

With this context I’m guessing the KMT’s primary opposition, the DPP, wants to highlight the KMT’s fascist legacy while also conflating the KMT’s and the CPC’s expression of Chinese nationalism. Making that false equivalency is easier because of the KMT’s interest in building stronger economic ties with the mainland.

Western media usually frames issues from the DPP’s perspective which would explain the commentary in the article.

also a deeply unpopular politician on the mainland so it's also a show of good faith

Removing his statues could be seen as white-washing the KMT's history, but I doubt anyone in the PRC is actually mad about it like the article claims.